1. Field of the Invention
The present invention relates to a semiconductor device and a method of fabricating the same, and more particularly, to a memory module having a star-type topology and a method of fabricating the same.
2. Description of the Related Art
Various electronic systems, such as personal computers, system servers, and communication equipment, employ memory modules as data storage devices. The memory module has memory devices and discrete devices that are attached to a printed circuit board. The printed circuit board is provided with tabs for electrical connection to an external connector.
The memory devices include volatile memory devices, such as Dynamic Random Access Memory (DRAM) or Static RAM (SRAM). The discrete devices can be resistors, capacitors, inductors, registers, programmable devices, or non-volatile memory devices. The discrete devices act to distribute external signals applied to the tabs to the memory devices for storage. Data stored in the memory devices can be read out through the discrete devices.
FIG. 1 is a plan view of a conventional memory module.
Referring to FIG. 1, the conventional memory module has memory devices 15 and discrete devices 17 which are attached to a substrate 11. Tabs 13 are disposed at an edge of the substrate 11. The substrate 11 and the tabs 13 constitute a printed circuit board. Reference symbol P denoted in each of the memory devices 15 is a mark indicating a position of pin No. 1 of the memory device 15, as a reference.
Substrate 11 commonly takes the form of a multi-layered substrate formed by attaching four to eight-layered substrates to each other. The tabs 13 can be electrically connected to the memory devices 15 and the discrete devices 17 through interconnections formed within the substrate 11. In addition, the tabs 13 electrically connect the memory devices 15 and the discrete devices 17 to an external device.
The substrate 11 can have a long axis and a short axis. The memory device 15 can also have a long axis and a short axis. The short axis direction of the memory device 15 can be disposed in parallel with the long axis direction of the substrate 11. That is, the memory devices 15 can be arranged in a vertical direction. However, the memory devices 15 can have various sizes depending on high integration and large capacity. For example, a mass storage memory device 15′ can have a larger external dimension than the memory devices 15. In this case, it is impossible to arrange the mass storage memory device 15′ in two rows in a vertical direction relative to the substrate 11.
Most topologies of the conventional memory module are T topologies. However, as the size of a package increases with an increased density, it becomes more difficult to dispose within the limited substrate 11 the memory devices 15 which were typically arranged in a direction vertical to the substrate 11, as shown in FIG. 1. Accordingly, the memory devices 15 are disposed in both horizontal and vertical directions with respect to the substrate 11, or are disposed in the horizontal direction only. As a result, it becomes more difficult to implement a configuration of the topology and signal connection between the memory devices.
Consequently, a technique is needed that can effectively dispose memory devices on a substrate to keep lengths of internal interconnections between the memory devices and the topology uniform and short.